The linebacker was forced out of the NFC West side's game against the Indianapolis Colts with the injury, before missing last Thursday's clash with the St Louis Rams.
The 28-year-old told the team's website: "Only thing I can do is have the right mindset and listen to my trainers and my strength and conditioning coaches.
"So far, each day has been good. Now, it's just making sure I stay on pace and don't try to do too much, but make sure if I'm going to be out there that I can help my teammates win.
"I've endured a lot of pain in all the years I've played football. There are some things my body is able to absorb, this right here, it was a little different. It was something new. I just thank God the MRI showed it wasn't something that was going to keep me out for the rest of the season."
Willis did not take part in full contact drills, but is optimistic of playing against the Houston Texans this weekend.